A locking mechanism for a shoulder strap of a backpack is disclosed which has guiding means, retaining means, and engaging means, where the engaging means is rotatable about an axis and slidably guided along the guiding means, where in a first rotational position the engaging means engages the retaining means so that a sliding movement of the engaging means along the guiding means is restricted, and where in a second rotational position the engaging means disengages the retaining means so that a sliding movement of the engaging means along the guiding means is enabled.